1. Field of the Invention
The present invention relates to an illumination apparatus, and particularly to an illumination apparatus to be used with image pickup apparatuses, such as digital still cameras and video cameras, to illuminate a predetermined area as an auxiliary light source.
2. Description of the Related Art
Electronic flash apparatuses as illumination apparatuses whose illumination angle is changeable with focal length of an image pickup lens. For example, Japanese Patent Laid-Open No. 09-138449 discloses a flash apparatus in which a light source and a movable reflector are integrally moved to change an illumination angle. In this flash apparatus, light proceeding toward outside the movable reflector is reflected by a fixed reflector to prevent loss of light quantity.
Moreover, Japanese Patent Laid-Open No. 2005-043688 discloses a flash apparatus in which a light diffuser provided with concave cylindrical lenses and convex Fresnel lenses is disposed further on an object side than a reflector to compensate for lack of light distribution to a peripheral part of an illumination area.
However, with increase of zoom ratio of image pickup lenses, a flash apparatus having a larger changeable range of the illumination angle is required.